The present invention relates to a fluid-operated wrench.
Fluid-operated torque wrenches are known in the art. All hydraulic torque tools provided with a cylinder-piston unit operate so that when a piston moves in one direction to act on an engaging member which engages a threaded connector for loosening or tightening the latter, a cylinder of the cylinder-piston unit moves in an opposite direction and is made to abut against a stationary object. The engaging member which is connected with the threaded connector to be turned is subjected to the pulling force which tends to pull the engaging member from the threaded connector to be turned. In other words, when the cylinder of the cylinder-piston unit reacts against a stationary object, the force opposite to the reaction force pulls the engaging member laterally or radially from the axis of the threaded connector to be tightened or loosened. It is to be understood that when the engaging member is formed as a socket or box wrench which surrounds a threaded connector over its entire circumference, this pulling force does not cause any problems. However, when the engagement member is formed as an open-end wrench or in other words, extends only over a part of the circumference of the threaded connector, the pulling force urges the engaging member from the threaded connector.